The interests of the Varki lab are focused on a family of sugars called the sialic acids, and their roles in biology, evolution and disease. Sialic acids are found at the outermost position on the glycan chains of all vertebrate cell surfaces and glycoproteins, and the highest levels are found in the nervous system. Currently active projects are relevant to the roles of sialic acids in microbial infection; the regulation of the immune response; the progression of cancer; and unique aspects of human evolution. We are particularly intrigued about finding multiple differences in sialic acid biology between humans and our closest evolutionary cousins, the great apes. These differences are a signature of the events that occurred during the last few million years of human evolution, and may be relevant to understanding aspects of the current human condition, both in health and disease. Interest is also directed towards the potential impact of the uniquely human sialic acid profile on the brain. These specific research directions have also lead to a broader interest in explaining the origins and workings of the human phenomenon.